1. Field of the Invention
This invention relates to a method and apparatus for cleaning a conveyor belt and, more particularly, to a cleaning roller and its operation.
2. Description of the Prior Art
As has been well known for many years, conveyor belts have been used in a wide variety of machines, and in various applications, primarily to convey articles or material from one point to another. A problem associated with conveyor belts is the build-up of residue which occurs when certain materials are being conveyed. Conveyor belts for materials such as coal, coke, woodchips and the like continuously collect and retain residue after discharge of the bulk of the conveyed material from the conveyor. A portion of this residue material is deposited onto idler and support pulleys as well as various other mechanisms, thereby creating maintenance problems and high operating costs. As a result of this residue problem, various cleaning devices have been used to scrape or otherwise clean the residue from the conveyor belt. These scraping and cleaning devices have included brushing mechanisms, scrapers, knife-edges, rotary drums, flexible blades and the like which all contact the conveyor in some manner, and which engage the residue material deposited thereon to remove it from the conveyor.
A representative cleaning device is disclosed in U.S. Pat. No. 3,583,555, which utilizes a contacting roller to engage the surface of the conveyor belt. The contacting roller is rotated in a direction opposite to the path of travel of the conveyor belt. A single set of helical formation having specifically configured serrations along their top face are rotated at a high rate of speed to engage and remove the residue deposited on the conveyor. This particular mechanism has been marketed by Surfbelt, Inc. of McKeesport, Pa. for cleaning large industrial conveyors which carry coke, coal, woodchips and the like.
A number of drawbacks are inherent in the referenced device which, by their very nature, limit the use of this conveyor cleaner to only large industrial applications. The cleaner utilizes an offset drive motor which, through a sprocket and drive belt, rotates the contacting roller. An adjustment mechanism moves the contacting roller, frame member and motor relative to the conveyor. The frame member is extremely cumbersome and heavy due to the various members it must support. The adjustment mechanism employs a number of tension springs and adjustable mounting brackets which must move in order to maintain contact between the conveyor and contacting roller. Accordingly, the mechanism is quite large and is only capable of coarse adjustments due to the requirement that it be capable of adjusting the position of the heavy contacting roller and frame member. The referenced device cannot be used in applications where small positional adjustments may be necessary.
Further, the contacting roller is provided with helical formations which extend about the roller. These formations cause the generation of a force, as the contacting roller engages the conveyor belt, in a direction parallel to the contacting roller's axis of rotation. This force tends to make the roller and belt move relative to each other in a direction perpendicular to the path of the conveyor. This force generation requires a large frame member to restrain any resultant movement of the contacting roller.
Another known conveyor belt cleaner employs a coaxially aligned drive motor and contacting roller. Although the overall weight and size of the frame member is decreased, it still remains relatively large in order to accommodate spring-loaded slip-plates which move the contacting roller, drive motor, and entire assembly relative to the conveyor in an effort to maintain sufficient contact between the conveyor and the roller. Further, the frame member also is large in order to withstand the axial force inherently generated by the single set of helical formations.